Scanners are widely used which read an image of an original as a subject such as paper, a photograph or the like and generate image data corresponding to the image. A CCD or the like is used in a scanner.
Such a scanner repeats control such that after the CCD reads an image of a predetermined area of an original, the CCD is moved and a shutter of the CCD is operated so as not to pick up an image of another area of the original, and when the CCD reaches a next area to be read of the original, the shutter of the CCD is operated so as to pick up an image. Thereby images of desired areas of the original are read.
In order to improve resolution, however, the shutter needs to be operated so as to pick up only an image at a predetermined position of a narrower area of the subject in response to movement of the CCD in a scanning direction, thus resulting in a problem of a shorter image pickup time of the CCD and hence a degraded S/N of image data obtained. In order to shorten reading time, the shutter needs to be operated so as to pick up an image in a shorter exposure time in response to movement of the CCD in the scanning direction, thus resulting in a problem of a shorter image pickup time of the CCD and hence similarly a degraded S/N of image data obtained.
In addition, in image pickup by a mechanical shutter, the shutter needs to be opened and closed frequently in response to movement of the detecting element, thus resulting in a problem of increased load on the mechanism and hence susceptibility to failures. In this case, there is also a problem of increased power consumption when the mechanical shutter is operated frequently.
Furthermore, in order to lengthen image pickup time simply for higher S/N of image data, the CCD needs to be stopped at each image pickup position of the subject, thus resulting in a problem of long reading time.